This invention relates generally to the automatic operating machines, and specifically to the packing machines of the type wherein the intermittent or step-by-step movement of a driven portion of the machine, is coordinately, selectively and at due time off the timely intermittent movement of a driving portion of said machine.
In certain machines of the type specified above, the problem often arises to transmit said intermittent motion from said driving portion of said driven portion of the machines exactly according to the operative timed relationship between the portions of said machines.
Stated otherwise, the problem arises to discontinue coordinately and selectively the transmission of the intermittent motion, and respectively to resume it, from the driving to the driven mechanisms, exactly in accordance with the timing characteristics of the intermittent motion between these two driving and driven mechanisms.
Specifically, the invention relates to the case wherein said intermittent motion to be transmitted and interrupted in a controlled and timed manner is an intermittent regular positive rotation, or step-by-step rotation, of a drive shaft which is forced to effect constant timed revolutions, each of a one-revolution amplitude, or of an integer fraction of one revolution, individually intercalated with timed dwell periods of said shaft.
Generally speaking, said shaft receives said intermittent rotation from said driving portion of the machine through a rotary driving member, such as a toothed wheel keyed on said shaft, and transmits said rotation to an associated driven portion of the machine through a rotary driven member which could be, generally, another toothed wheel rotatably mounted on said shaft and is operatively associated with a controlled coupling device for the timed coupling and uncoupling of the driven wheel with respect to said intermittent drive shaft.
A controllable coupling device for the timed rotational coupling and uncoupling of a driven member of a machine with respect to a driving member having a regularly intermittent rotation has already been proposed; however, said device is relatively complicated, requires the use of an auxiliary shaft having a continuous rotary movement, and is not suitable for very high production rates, because the coupling and uncoupling operations effected thereby require the axial displacement of a cylindrical cam along said auxiliary shaft, which implies a response time which is not entirely satisfactory.
In order to comply with the mechanical requirements of the ever growing production rates of the present packing machines and the like, this invention proposes a reversible, rotary, controlled, axial-engagement, quick-coupling device suitable for an in-line, timed transmission of an intermittent rotary motion, even of reversible type, from a drive shaft, regularly rotating step-by-step, to a rotary driven member, such as a toothed wheel, co-axial with said shaft, wherein the intermittently-rotating drive shaft is solid with a co-axial transfer disc or flange having generally an annular series of keyways, corresponding in number to the steps of the intermittent motion in one revolution, starting from a single keyway in case of a maximum one-revolution step, while the driven wheel, which is freely rotatable on the intermittent shaft, has embedded therein, parallelly to said shaft, a spring-loaded latch urging with an end thereof against an annular region of said disc at the keyways thereof, and cyclically collimates axially with each successive pusher of a series of regularly-arranged controlled pushers, which are in the same number as said keyways and are angularly positioned in registry with the dwell positions of said intermittent shaft, whereby each pusher, under the action of a respective control means, such as a pneumatic cylinder, abuts end-to-end against the latch and pushes it back into the driven wheel so as to disengage it from the respective keyway of the disc, while holding said wheel in a stationary position whereas said disc is free to follow at all times the intermittent movement of the shaft.